In the field of print-duplication, improvements in working efficiency in the photomechanical process is required to improve the diversity and complexity of printed matter.
In particular, in the work of page make-up and dot to dot work stages, effort has been directed toward improving working efficiency by working under brighter light conditions. For this reason, bright room-type silver halide photographic materials for the photomechanical process which are treatable under daylight conditions and exposure printers have been developed.
The bright room-type silver halide photographic material described in this specification means a photographic material for which light free of ultraviolet light components and having a wavelength of 400 nm or more can be used as a safelight light.
The bright room-type silver halide photographic material for use in the work of page make-up and dot to dot work stages is a photographic material used to perform negative image/positive image conversion or positive/negative conversion using a processed film on which characters or halftone images are formed as an original, and by subjecting the original and a silver halide photographic material for dot to dot work to contact exposure. For these silver halide photographic materials, the following characteristics are required and bright room-type silver halide photographic materials for dot to dot work which meet the requirements have been developed:
(1) They must function to convert halftone dot images, line images and character images from negative images to positive images depending on the area of the halftone dot, the width of the line and the width of the character, respectively. PA1 (2) They must function to control the tone of the halftone dot images and the line width of the character images and the line images.
However, bright room-type silver halide photo-graphic materials have the disadvantage that the density of a portion ordinarily developed and turned black over the entire surface thereof tends to be significantly reduced, when under-exposure is used to control the tone of the halftone dot images in the dot to dot work stage using the above bright room-type silver halide photographic materials.
Methods for obtaining high contrast and an increase in Dmax by adding developing agents to silver halide photographic materials are disclosed in U.S. Pat. No. 4,617,258, JP-A No. 59-171947 (The term "JP-A" as used herein means an "unexamined published Japanese patent application"), JP-A Nos. 59-206828 and 1-262533. However, they do not satisfy all functions of safelight, shelf life and Dmax. In addition, methods in which impurities (heavy metals) are present in the crystals of the silver halides are disclosed in European Patent Nos. 336,427 and 336,689. However, the shelf life is inferior and the Dmax is not stable.